Feasibility Study of Microneedle Fabrication from a thin Nitinol Wire Using a CW Single-Mode Fiber Laser

Abstract

In this paper, feasibility studies are presented on microneedle fabrication by using a multiple-pulse laser microhole drilling technique to drill an axial hole into a thin nitinol wire of 150 μm in diameter. Nitinol is chosen for its biocompatibility and excellent super-elasticity to eliminate breakage risk. One potential use of this microneedle is for drawing a small amount of blood for glucose monitoring. The critical factor for drilling microholes into a thin nitinol wire axially is the restoration of the semi-infinite material condition, which is the key to prevent the thin wire from being melt away by the laser due to excessive heat transfer in the radial direction. The results show that holes, up to 607 μmin depth, can be drilled into a thin nitinol wire of 150 μm in diameter using 18 repetitions of a 3-pulse group with 13 μs pluses. However, hole quality is poor. The challenges for improving hole qualities, such as centering, hole blockage, through holes, and process parameters, are discussed.

Keywords

• microhole drilling
• laser drilling laser ablation
• microsecond pulse
• fiber laser
• nitinol
• super-elasticity
• microneedle drilling